Five years ago, the Tufts Nutrition Collaborative - Center for Drug Abuse and AIDS Research (TNC-CDAAR) was funded by NIDA as just one of two CDAAR's in the nation. The CDAARs were charged with the following mission: to foster a collaborative approach to drug abuse and addiction research;to enable studies that would not occur without the climate, facilities, and resources that a research center can uniquely provide;to serve as a resource to attract established and promising investigators into drug abuse research; and to provide opportunities for research training, career development, and mentoring. The TNC-CDAAR was formed as a partnership between three East Coast Institutions (Tufts, Brown and Johns Hopkins) with a specific focus on studying nutritional and metabolic disorders among HIV-positive and HIV-negative drug users. Over the past five years, we have expanded the TNC-CDAAR to include collaborators from 3 international sites: Argentina, India, and Vietnam. Our major accomplishments, thus far, have been to 1) design and implement several new studies to assess and compare the prevalence and incidence of specific nutritional and metabolic disorders in drug users of different ethnicities, both in the U.S. and abroad;2) develop training materials, protocols, and manuals for investigators who want to undertake similar studies in their localities;3) help in the development of new grant proposals in Center-related areas of research;and 4) become a resource center on nutrition and metabolic disorders in drug users. Specifically, he Epidemiology and Biostatistics Core (Core F) will provide a wide range of services to Center Members to facilitate the design, collection, and analysis of nutritional and metabolic complications of HIV infection, recreational drug use, Hepatitis and liver disease among studies of injection drug users (IDUs) from the collaborating institutions. The major role of the Epidemiology and Biostatistics Core will be to increase the efficiency of data collection and analysis for Center Members at the collaborating institutions and to institute quality assurance procedures for all centralized data collected (See Section III below for listing of specific Core services). The Core will benefit from the expertise of two epidemiologists (Drs. Tang and Forrester) and a statistician (Dr. Terrin), all from Tufts University. Our team has worked together for several years on multiple cross-sectional and longitudinal datasets of drug users from Baltimore, Boston, and Providence. Dr. Terrin has developed models for longitudinal cohort studies to accommodate the inconsistent nature of drug use, allowing for the examination of use and duration of use for specific types of drugs on outcomes of interest.